Phthalocyanine pigment



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Elli) es Augustinus Dahlen and Stanley Rawlings Detrlck, Wilmington, DeL, assignors to E. li. du Pont de Nemours & Company; W 1 w I gton, Deb, a corporation oil Dela No Bra.

This invention'relates to colored organic pigmerits. More particularly it relates to processes for modifying the physical properties of phthalocyanine pigments.

It is an object of this invention to prepare phthalocyanine pigments of improved physical properties, which will adapt them better for their various uses in the arts of making printing inks, lacquers and paints. It is a further object of this invention to provide a method for controlling the physical properties of phthalocyanine pigments, especially as they relate to masstone, brightness, and tinctorial strength. It is a further, special object of this invention to prepare copper phthalocyanines, or other specific phthalocyanine compounds, in a form which gives a printing ink of jet masstone efiect. Other and further useful objects of this invention will appear as the description proceeds.

In the manufacture of organic pigments, numerous physical properties of the products determine their commercial value. Obviously high tinctorial value is most important. However, when deep shades are desired in printing inks, synthetic finishes, etc., the property of masstone is likewise very important. Masstone is defined as the color which a pigment has when a film o1 it is viewed by reflected light and when the film is of sufiicient thickness to prevent any light from the background from filtering through. Usually jet masstones are desired. The qualification jet implies that the color observed is free of whiteness or milkiness.

The quality of brilliance or brightness is, of course, also important. As in all other manufacture of synthetic dyes, maximum brilliance always is an objective.

In the case of toners and lakes produced from azo colors containing acid groups, the control of their physical properties, such as tinctorial value, masstone, etc., is generally efie'cted by the physical conditions under which the pigments are synthesized or laked. In the phthalocyanine pig ments, however, the products are purified by acid-pasting. This is a procedure commonly followed in the preparation of vat dyes but hitherto virtually unknown in the manufacture of pigments. The investigations of conditions for acidpasting have in the past all been directed toward securing optimum dyeing characteristics in the colors, not toward producing colors of optimum pigment properties.

Now we have discovered that the physical characteristics of a phthalocyanine pigment can be readily controlled by modifying the conditions of more fully illustrate Application September 10,,1987, Serial No. 163,242

(cl. ice-st) acid pasting in a novel and unforeseen manner. More particularly, we have found that the physical qualities oi? the resulting pigment can to a certain extent be controlled and modified by co' precipitating with the principal phthalocyanine 5 coloring matter a small quantity of a difierent phthalocyanlne compound hereinafter referred to as the control.

The result is quite surprising, because it was to be expected that the control would adulterate the principal color and afiect detrimentally its brilliance as well as possibly other physical properties thereof. In the case of dyes, for instance, it is a well known principle that mixing colors dulls the shade. It was very much'surprising that in the ease of coloring matters of the phthalocyanine series, there are not only no detrimental efiects on the brightness, but on the contrary, the latter is in most cases improved. The tinctorial strength'is likewise increased in most cases in a surprising manner. In addition, the masstone of the pigment is generally improved, being rendered more jet than the masstone of the pure principal.

The above effects are particularly surprising in View of our observation that mere intimate mixing oi the principal and color, for instance by milling, does not produce the improvements above noted. Our invention demands that the two colors be co-preclpitated from a joint solution, which is most conveniently done by acidpasting the two jointly as above set forth.

Accordingly, our invention comprises in principle the following steps:

A principal phthalocyanine pigment is mixed with a small percent of another phthalocyanine pigment and the mixture is dissolved in concen-- trated sulfuric acid or an equivalent solvent. The solution of the pigment mixture is drowned in a suitable quantity of water under proper conditlons of temperature, agitation, etc. At this point, the two pigments are co-precipitated. .I'he pigment suspension is filtered and washed acidfree. It may be washed further, treated with alkalles, assistants, etc., and again filtered. The 46 final pigment cake is dried and ground. When the dried pigments are incorporated in a vehicle and compared with the same pigment precipitated in the absence of other 'phthalocyanines, marked differences in physical noted.

Without limiting our invention to any particular details, the following examples are given .to the same. Parts mentioned are by weight. 66

Properties are 50 lf-y 'l 1 TREATMENT or- Corm PHTEALOCYANINE 23.75 parts oi. copper phthalocyanine (Jour. Chem. Soc., 1934, pp. 1027-1031) and 1.25 parts of zinc phthalocyanine were added to 250 parts of 98% sulfuric acid at C. to C. The mixture was agitated until all of the pigment was in solution. The acid solution then was added slowly to 2500 parts of water at 95 to 100 C. The suspension was filtered and washed acid-free. The pigment cake was retumed' to a alkaline suspension containing 5 parts of 26% aqua ammonia. The suspension was illtered, washed alkali-free and dried at 90 to 100 C. I

Penrana'rron or Pnm'rmo INK The standard (in this case copper phthalocyanine precipitated in the absence of other phthalocyanines) was rubbed in exactly the same manner, and sample and standard were examined side by side on bond paper.

on comparing the sample with the standard,

thesample was found to he more jet in masstone.

TEST roa Bnmnrmzss AND Tmo'romr. VALUE 0.150 part of the above ink and 2.5 parts of zinc oxide ink were mixed with a spatula, rubbed out with a muller as described above and examined together In this case the sample was found to be slightly greener, brighter and equal in strength compared with the standard.

TREATMENT or METAL-FREE PHTHALOCYANINE phthalocyanine in Example 1.

All of these samples were tested against a sample of metal-free phthalocyanine precipitated in the absence of any other phthalocyanine. The results are shown in Table II.

Table 17 Comparison with unadulterated Comm pmhalm metal-free phthalocyanine cyanineused Masswne Shade Strength Zinc phthalocyanlne..- Morejetn Mgeh red- Equal.

. er. Cobalt phthslocysnlne. ...do do 2.5% stronger. Nickel phthelocyanine. do do E gual. Copperphthalocyanine. .-.do. vegdmuch 5 stronger.

r er. Lead phthalocyanine ..do Mich red- 5% weaker.

- er. Barium phthalocya- ...do... do 10% weaker. Alum inumphthalocyw do do 10%weeker.

nine.

ELE 3 I TauA'rMnnr or ALUMINUM Pn'rnsmoranmn copper phthalocyanine.

The results are shown in Table m.

Another series of pigment preparations was made in which aluminum phthalocyanine (Br. Patent No. 410,814) was co-precipitated with other, control phthalocyanines. The same procedure and ratio was followed as described for Table III Comparison with unadulterated aluminum phthslocyanine Control phthalocynnins need Messton'e Shade Strength Zinc hthnloeyenine Vexnightly milky Slightly green. slightly bright. 126% tron CObo t phthalocynnlne. Ellig tly milky Red 22%; stronger- Nickel phthalocysnine Very slightly milky Slightly red brhzht..- 12% 0 stronger. Metal-free phthalocyanine do 134% St g Lead phthalocyanlne do do D0- Barium phthalocyenine Close Slightly bright D0. Copper phthalocyanine Slightly mllky Slightly red bright. 5 7241% stron Following the above-described technique, a WW 1 number of other control phthalocyanines were TREATMENT OF Gm omum COPPWPHTHALO.

co-precipltated with copper phthalocyanine in the same ratio as above. The results obtained are given in the following table.

GYANINE 23.75 parts oi. chlorinated copper-phthalocya nine (-16 chlorine atoms per molecule; co-

Table 2 00m arisen with unadulterated e0 hthalocyanlne Control phtheloey p mm P no need Maastone Shade Strength Cobaltphthaloeyanlne. Very et V slightly red 107 ctr-om Nickel phthalooyanlne. "ma fil tly green bright-. n fml. Metiill-free phthalocy- J on 9. Lead phthalocyenine.-- ..-do do Do. Barium phthalocyanlne Slightly jet do 8% stronger. Aluminum phthelocy- Much more let.. Greener brighter 2.6% stronger.

anlne.

aicaros pen I. 1: application of Fox. Serial No. 149,884) and I25 parts of zinc phthalocyanine were added to a ture of 187.5 parts of sulfuric acid monohydrate and 62.5 parts oi chloro-sulfonic-acid at C. to C. The mixture was agitated until sion was filtered, washed alkali-free and dried at 00 to 100 C.

The method of testing the dried pigment was similar to that described under Example 1. In other experiments, in place of zinc phthalocyanine, equal amounts of various other control phthalocyanines were substituted.

- All of the above samples were tested against a sample of the same chlorinated copper phthalocyanine precipitated in the absence of other phthalccyahines.

The results are shown in Tahle Il mixed, the solids adjusted to 10% and the paste milled through a colloid mill. The product was dried at 90 to 100 C. Similarly, two other samples were prepared containing 2% and 5% of aluminum phthalocyanine, respectively. These samples were tested against a sample of the same precipitated copper phthalocyanine containing no other phthalocyanines. The results are shown in Table VI.

Table Vi I Comparison with copper phthelocysnine Percent aluminum Table IV Comparison with unadulterated chloro- Control phtham copper-phthalo yanine cyanine was" Messtone Shade Strength Zing: phthalocya Vcryjet..... Very hlue.. W, stronger.

n no. Col mltphthalocyado Blue, dull--. 15%stronger.

nee. Nlcillzlelphthalocya- Jet ..do 10% stronger.

n e. Metal-ireephthalodo do 714% stronger.

cyanine. Lead phthelccym ....do Blue Equal.

no." Barign'n phthalocy- Slightlyjet" Slightly blue D0.

an no. Aluminum phthal- Very jet Blue, slightly Do.

oeyanine. dull.

EXAMPLE 5 VAEYING ma AMOUNT or CONTROL procedure was followed as described in Example l.

The samples were tested against the same sample of crude copper phthalocyanine, precipitated in the absence of other phthalocyanines. The results are shown in Table V.

Table V Amount of Comparison with unadulterated copper aluminum phthslocyanine phthalocyanine used, based on Masstone Shade Strength More jet Greener, slightly 2.5% stronger.

brighter. .do do Do. hilugh more Greener, brighten Do.

phthalocyanine used M tone Shade Strength 010%.... Greener-.. Equal. l-.do ...do Do. do do Do.

It is readily seen that the mere mixing oi the two acid-pasted pigments causes no difierence in either masstone or brilliance.

'Although the above examples illustrate the in vention only as it is applied to a few of the phthalocyanine series, it will be readily appreciated that it may be applied to other pigments of this series.'

Although not less than 1% nor more than 5% of the co-precipitated control phthalocyanine was used in the examples, our invention is not limited to these quantities. Furthermore, the conditions of the precipitation, such as the amount of sulfuric acid used, amount of drowning water, temperature of solution and temperature of drowning may be varied over wide limits without defeating the object of this invention. Although the specific examples disclose only the co -precipitationof principal phthalocyanines plus control phthalocyanines from sulfuric acid solution or from mixtures of sulfuric acid and chlor-sulfonic-acid, it is obvious that other solvents may be employed. Of particular interest in this connection are phosphoric acid, anhydrous hydrofluoric acid, oleum and trichlor-acetic-acid. In general, our invention depends upon co-precipitation from a solution of the principal and control pigments, regardless of the nature of the solvent.

The advantages of our invention will now be readily apparent. It is known that phthalocyanine pigments, when used in full shades, have a milky or light appearance. This is especially characteristic of copper phthalocyanine. The trade, however, insists on a deeper, more jet shade. Furthermore, the trade demands a hit brighter shade in tints where the colored pigment is mixed with whites.

By the method of this invention we have found a simple and reliable method for controlling the jetness of the masstone and for increasing the brilliance of shade. The pigment obtained by this process shows an increased jetness and brilliance over untreated pigment. As will be obvious from the examples, in certain instances the tinctorial value of the pigments is also increased. This of course is an economic improvement over products of the prior art.

Stated .briefly, our present invention makes possible the modification in an economical manner of the physical properties of phthalocyanine pigments, without sacrificing any of their outstanding fastness properties.

As is well known the phthalocyanine pigments now find important commercial use in the preparation of printing inks, paints, enamels, lacquers, colored rubber articles, colored paper, 001- ored plastics, etc.

We claim:

1. The process oi preparing a, phthalocyanine pigment in an improved physical condition, which comprises dissolving the sameiin an acid solvent jointly with a. different phthalocyanine pigment,

the quantity of the latter being not over 5% by weight of the former, and then precipitating S AUGUSTENUS DAIEHJEN.

1i MWGS DEIRICK. 

